Just saw a really cute guy

I live in an apartment complex and went to the concierge to pick up a package after I'd been to the gym. I was in my gym gear & noticed a cute guy walk in and he checked me out then went off somewhere. He came back in a few minutes later also to collect a package whilst mine was still being looked for. Mine came so I walked out of the building back to my apartment, then as I was leaving my apartment building he was walking in. I held open the door for him, he thanked me and I said it was OK. He is so cute. I know what flat number he is in as I overheard him telling the man at reception.Should I have made convo when I saw him the second time? I really want to see him again What to doooo